The state has notified more than 150 school systems that the annual grants they receive to fund full-day kindergarten may cease July 1.

The state Department of Elementary and Secondary Education began its Kindergarten Expansion Grant Program in 2000. The grant, known as 701, encourages the voluntary development of full-day kindergarten classes and supports the quality of existing programs.

The grant program, subject to annual funding by state lawmakers and the governor, awarded $22.9 million to 162 school systems last fiscal year.

“The department is considering restructuring funding and targeting grant awards in future years to high-need districts,” DESE Commissioner Mitchell D. Chester wrote in a September report to the state Legislature.

The proposed restructuring would restrict eligibility to underperforming schools with high populations of students from low-income families.

School systems losing the grant would face difficult choices, such as reverting to half-day programs, charging or increasing tuition, reducing staff, or cutting elsewhere in the operating budget.

Those at risk include Worcester public schools, Webster public schools and the Dudley-Charlton Regional School District.

Dudley-Charlton used the 701 to begin its full-day kindergarten in 2001 and has received funding each year since. Today, the district operates a $1.3 million program with 12 classes totaling 273 students.

The grant provided $135,000 this year.

“Funding for full-day K is in jeopardy at this time,” said Sean M. Gilrein, Dudley-Charlton superintendent of schools. “If the priority changes, we would not be eligible to apply and we would lose that money.”

Mr. Gilrein said the full-day program has been statistically proven to improve academic readiness and has enhanced students' cognitive, language and social development.

Although it's too early to know the consequences of losing the grant, he said, Dudley-Charlton administrators are committed to maintaining the quality of the full-day program.

The Worcester public schools received $974,034 this year toward free, full-day kindergarten. The grant pays a portion of the costs, said Gregory Bares, manager of grant programs.

According to the school budget, most of the money is spent on 67 instructional assistants for kindergarten classrooms, covering about half that cost.

Any loss, Mr. Bares said, “would obviously put a strain on the district budget.”

The Webster public schools received $78,764 to support 152 kindergarten students in seven classes.

Webster Superintendent of Schools Barbara Malkas said: “This grant used to be a very robust program assisting districts to implement full-day K. It has been cut significantly for the last five years.”

When Webster chose to go to the full-day, Ms. Malkas said, it did so knowing most of the cost would be borne locally.

“If these funds are gone, we still have to find the funds somewhere else because we have a population of children who need to be prepared for their education,” she said.

While 162 school systems relied on the state to subsidize kindergarten costs in 2012, others forgo the grant and its many stipulations.

Superintendent Maryellen Brunelle said the Auburn public schools initially offered full-day kindergarten as an option to families who chose to pay tuition of $2,160 per year. It became fully funded by the school's general fund last year.

Oxford has been funding its full-day program from its operational budget for the past two years, said Superintendent Allen Himmelberger. Before that, the school system offered a series of half-day kindergarten programs.

Jonathan Considine, DESE spokesman, said half a day of kindergarten is mandatory and funded by the Chapter 70 formula used for Grades 1-12. Presently, school systems that offer free, full-day classes are eligible for the grant to support costs associated with the second half of the day.

School systems that lose the grant, he said, would gain some Chapter 70 aid.

The DESE decision is expected soon.

“We recognize that school districts are currently planning their fiscal '14 budgets. We are committed to providing timely information for planning and budgeting purposes as soon as we can,” Mr. Considine said.

The DESE reported that the share of Massachusetts children enrolled in full-day kindergarten increased from 29 percent in 2000 to 83 percent in 2012.

Jacqueline Reis of the Telegram & Gazette staff contributed to this report.